1. Field of the Invention
The present invention relates to an electron-beam data generating apparatus for converting layout pattern data into electron-beam data (EB data) for creating a mask to be used in a semiconductor fabrication process.
2. Description of the Prior Art
In order to manufacture a semiconductor integrated circuit (LSI), in general, after the design of the LSI has been completed, a circuit pattern of the LSI is created as a metallic thin film on a glass substrate. The metallic thin film forming the circuit pattern of the LSI is referred to as a mask. Semiconductor devices are then created by transferring the circuit pattern to locations on a silicon wafer sequentially one location after another by using the mask. A mask is created normally by, first of all, converting a circuit pattern resulting from a completed layout design into mask data having a data format readable by a mask drawing apparatus. In the following description, the circuit pattern, data input to the format-conversion process, is referred to as layout-pattern data which has a GDSII STREAM format. On the other hand, mask data output by the conversion is called as EB data.
When the designer creates layout-pattern data, a circuit pattern is entered for each fabrication process. At that time, it is necessary to enter figure data by providing a hierarchy thereto. The hierarchy comprises design layers. A segment is a drawing-region unit of the mask drawing apparatus. A mask is drawn by dividing the pattern of the mask into segment units.
FIG. 8 is a block diagram showing the configuration of a conventional electron-beam data generating apparatus for two design layers, two fabrication processes and two segments. FIG. 9 is a diagram showing an example of an image figure of layout-pattern data. In this example, the number of fabrication processes match the number of design layers. It should be noted, however, that one fabrication process may correspond to a plurality of design layers.
In FIG. 8, reference numerals 1 and 2 denote layout-pattern data and a stream analyzing unit respectively. Reference numeral 3 is a reference sorting unit and reference numeral 4 denotes a hierarchy developing unit. Reference numerals 5 and 6 are a trapezoid division unit and a trapezoid-file sorting unit, respectively. Reference numeral 7 denotes a data compressing unit and reference numeral 8 is a format converting unit. Reference numerals 9a and 9b each denote EB data.
The hierarchy developing unit 4 comprises a hierarchy developing L1 sub-unit 10 and a hierarchy developing L2 sub-unit 11 for developing hierarchies for design layers L1 and L2 respectively. The trapezoid division unit 5 comprises a trapezoid division P1 sub-unit 12 and a trapezoid division P2 sub-unit 13 for carrying out trapezoid division processes on data developed for fabrication processes P1 and P2 respectively. In addition, the trapezoid-file sorting unit 6 comprises a trapezoid-file sorting P1S1 sub-unit 14, a trapezoid-file sorting P1S2 sub-unit 15, a trapezoid-file sorting P2S1 sub-unit 16 and a trapezoid-file sorting P2S2 sub-unit 17 for carrying out trapezoid-file sorting processes for their respective combinations of the two fabrication processes P1 and P2 and segments S1 and S2 each used as a unit of mask-pattern creation. The data compressing unit 7 comprises a data compressing P1S1 sub-unit 18, a data compressing P1S2 sub-unit 19, a data compressing P2S1 sub-unit 20 and a data compressing P2S2 sub-unit 21 for sorting trapezoid files of their respective combinations of the two fabrication processes P1 and P2 and the two segments S1 and S2. The format converting unit 8 comprises a format converting P1 sub-unit 22 and a format converting P2 sub-unit 23 for format conversion to generate the EB data 9a and the EB data 9b of the fabrication processes P1 and P2, respectively.
First of all, from the layout-pattern data 1 created by the designer in the GDSII STREAM format, figure data of the stream data is read out by the stream analyzing unit 2 for each cell. At that time, only data of layers specified by parameter inputs is read in. Further, the stream format is checked and, in addition, data such as cell names and reference information is analyzed.
The reference sorting unit 3 then sorts reference files from the analyzed stream. Subsequently, the hierarchy developing unit 4 develops a cell hierarchical structure for each design layer, creating a flat figure on each of the fabrication processes. Then, the trapezoid division unit 5 carries out a trapezoid division process on the figure having a developed hierarchical structure for each fabrication process. The trapezoid-file sorting unit 6 then carries out a file sorting process on trapezoid data produced by the trapezoid division unit 5 for each segment. Subsequently, the data compressing unit 7 compresses the data for each fabrication process and each segment. Finally, the format converting unit 8 carries out format conversion for each fabrication process to produce a MEBES data format. The processing steps described above result in the EB data 9a and the EB data 9b.
In the hierarchy developing unit 4, the design layer L1 is processed by the hierarchy developing L1 sub-unit 10 and, as the processing is completed, the design layer L2 is processed by the hierarchy developing L2 sub-unit 11. In the trapezoid division unit 5, figures developed by the hierarchy developing unit 4 undergo processing for the fabrication process P1 by the trapezoid division P1 sub-unit 12 and, as the processing is completed, undergo processing for the fabrication process P2 by the trapezoid division P2 sub-unit 13. In the trapezoid-file sorting unit 6, files of the figures completing the trapezoid division processing are sorted by using data such as the X-direction coordinate or a data code resulting from coding of a trapezoidal shape, a stripe or a segment as a key. First of all, processing for the fabrication process P1 and the segment S1 is carried out by the trapezoid-file sorting P1S1 sub-unit 14. When this processing is finished, processing for the fabrication process P1 and the segment S2 is carried out by the trapezoid-file sorting P1S2 sub-unit 15. When this processing is finished, processing for the fabrication process P2 and the segment S1 is carried out by the trapezoid-file sorting P2S1 sub-unit 16. When this processing is finished, processing for the fabrication process P2 and the segment S2 is carried out by the trapezoid-file sorting P2S2 sub-unit 17. In the data compressing unit 7, processing for the fabrication process P1 and the segment S1 is carried out by the data compressing P1S1 sub-unit 18. When this processing is finished, processing for the fabrication process P1 and the segment S2 is carried out by the data compressing P1S2 sub-unit 19. When this processing is finished, processing for the fabrication process P2 and the segment S1 is carried out by the data compressing P2S1 sub-unit 20. When this processing is finished, processing for the fabrication process P2 and the segment S2 is carried out by the data compressing P2S2 sub-unit 21. In the format converting unit 8, processing for the fabrication process P1 is carried out by the format converting P1 sub-unit 22. When this processing is finished, processing for the fabrication process P2 is carried out by the format converting P2 sub-unit 23.
Having a configuration described above, the conventional electron-beam data generating apparatus has a problem that it takes a long time to carry out the processing to convert layout-pattern data into EB data.